1. Field of the Invention
The present invention generally relates to a hydraulic machine, and more particularly relates to a hydraulic pump health monitoring system and method thereof for a hydraulic machine.
2. Description of the Related Art
Abnormality detection devices for liquid pumps such as hydraulic pumps have been made known in Japanese Patent Application Laid-open No. S59-194215, Japanese Patent Application Laid-open No. H7-280688, Japanese Patent Application Laid-open No. 2000-241306, and Japanese Patent Application Laid-open No. H8-114183 for instance.
The hydraulic system failure detection device disclosed in Japanese Patent Application Laid-open No. S59-194215 detects factors (such as oil pressure and operating oil temperature or the like) which reduce the life of hydraulic system component units, determines a current momentary degree of reduction of life span based on the measured oil pressure and operating oil temperature, and determines the reduction in life span by a cumulating these degrees of reduction. Furthermore, this device has a warning mechanism which functions after a failure has occurred.
The device for determining wear of a pump shown in Japanese Patent Application Laid-open No. H7-280688 measures the flow in the case drain and the change in flow, and determines that a failure has occurred when a fixed threshold value is exceeded.
The pump failure diagnostic device disclosed in Japanese Patent Application Laid-open No. 2000-241306 has a metal sensor in a drain path and a flow sensor in a discharge path or drain path, and the measured value from one of the sensors is used as a parameter for correcting the detection value of the other sensor. For instance, when the flow rate measured by the flow sensor drops, and a determination is made that pump failure is progressing, a correction is made by applying a larger factor to the metal sensor measurement value, and thereby abnormalities can be more easily detected from the metal sensor measurement value. During normal operation, a separate failure diagnostic mode is provided, and in this failure diagnostic mode, a failure diagnosis is performed using the measurement value from the metal sensor while the pump output variable factors such as angle of inclination, engine speed, and pump load are fixed.
The pump lubrication system warning device shown in Japanese Patent Application Laid-open No. H8-114183 measures the flow rate of lubricating water which flows through the strainer of the pump lubricating system and the differential pressure across the strainer, and if the actual measured value of the differential pressure is greater than the predicted value predicted from the lubricating water flow rate, the strainer will be determined to be plugged and a warning will be issued.